This application is related to and claims priority from Japanese Patent Applications No. 2001-277055 filed on Sep. 12, 2001, No. 2002-174149 filed on Jun. 14, 2002, and No. 2002-203985 filed on Jul. 12, 2002, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a vehicle air conditioner for adjusting an air temperature blown into a passenger compartment by changing a ratio of a fluid flowing area to a non-fluid flowing area in a heating heat exchanger. Here, a fluid such as hot water, used as a heating source, flows in the fluid flowing area in the heating heat exchanger, and no fluid flows in the non-fluid flowing area in the heating heat exchanger.
2. Description of Related Art
Conventionally, an air mixing system and a hot-water adjusting system are known as an air-temperature adjusting system of a vehicle air conditioner. In the air mixing system, an air temperature to be blown into a passenger compartment is adjusted using an air mixing door, by adjusting a flowing amount ratio between hot air passing through a heating heat exchanger and cool air bypassing the heating heat exchanger. In the hot-water adjusting system, the air temperature blown into the passenger compartment is adjusted by adjusting a flowing amount or a temperature of hot water to be supplied to the heating heat exchanger.
In the air mixing system, an operational space of the air mixing door or a mixing space for mixing cool air and hot air is required in addition to a mounting space of the heating heat exchanger, thereby enlarging the size of the air conditioner. On the other hand, in the hot-water adjusting system, the mixing space and the operation space of the air mixing door in the air mixing system are not required. However, since the heat capacity of the heating heat exchanger is large, the air temperature cannot fast respond to a change of the flowing amount or the temperature of hot water flowing into the heating heat exchanger. Further, in a flowing-amount adjusting system of the hot-water adjusting system, the heating heat exchanger has the following heat radiation characteristics. That is, after a hot water valve is opened, as the flowing amount of hot water flowing into the heating heat exchanger increases in a small flowing amount range, the air temperature from the heating heat exchanger is rapidly increased. Thereafter, as the flowing amount of hot water increases, the air temperature from the heating heat exchanger is slowly increased. Therefore, it is difficult to continuously adjust the temperature of air blown into the passenger compartment from a low temperature range to a high temperature range.
In order to solve the problem, a hot water valve is required to accurately adjust a flowing amount of hot water in response to an operation stroke of the hot water valve in a small flowing amount range. However, in this case, production cost of the hot water valve is increased. Further, in the flowing-amount adjusting system, since hot water is supplied to the heating heat exchanger using a hot water pump driven by a vehicle engine, the air temperature tends to be changed due to a rotational speed variation of the engine. Further, the air temperature blown into the passenger compartment tends to be changed due to a flowing amount variation of air passing through the heating heat exchanger.
The present invention has been made in view of the above problem, and its object is to provide a vehicle air conditioner which can adjust temperature of air blown into a passenger compartment by using an air mixing function while having a reduced size.
According to the present invention, in a vehicle air conditioner, a heating heat exchanger for heating air using a fluid flowing therein as a heating source is disposed in an air conditioning case, and a flow control member is disposed within the heating heat exchanger to divide the heating heat exchanger into a first area where the fluid flows and a second area where the fluid does not flow. In addition, a ratio between the first area and the second area is changed by the flow control member. Accordingly, air is heated by the fluid in the first area of the heating heat exchanger to become hot air, and air passes through the second area of the heating heat exchanger without being heated in the second area. That is, air flowing from the second area of the heating heat exchanger is cool air. Thus, by changing the ratio between the first area and the second area in the heating heat exchanger using the flow control member, a flow ratio between a hot air amount and a cool air amount can be adjusted so that the temperature of air blown into the passenger compartment can be suitably adjusted. Further, because the flow control member is disposed in the heating heat exchange to control the fluid flowing area in the heating heat exchanger, an operation space of an air mixing door in a general air mixing system is unnecessary outside the heating heat exchanger, and the size of the vehicle air conditioner can be greatly reduced.
Preferably, the heating heat exchanger has a plurality of tubes through which the fluid flows to heat air. Further, the flow control member is disposed to change a ratio between a first number of the tubes in which the fluid flows, and a second number of the tubes in which the fluid does not flow. Accordingly, the flow ratio of the hot air amount and the cool air amount can be readily changed using the flow control member.
Preferably, the heating heat exchanger includes a core portion having the tubes, and a tank member for distributing the fluid into and for collecting the fluid from the tubes, and the flow control member is disposed in the tank member to be movable in the tank member so that an inner space of the tank member is partitioned in a tube arrangement direction where the tubes are arranged. Further, the flow control member is moved linearly in the tube arrangement direction to change the ratio between the first number of the tubes in which the fluid flows, and the second number of the tubes in which the fluid does not flow. Therefore, the flow control member can be readily disposed in the tank member of the heating heat exchanger while having the air mixing function.
Specifically, in this case, a screw rotation shaft extending in the tank member in the tube arrangement direction is disposed in the tank member, and the flow control member is fitted with an inner surface of the tank member to form a fitted state which prevents the flow control member from being rotated relative to the tank member, while being slidable on the inner surface of the tank member in the tube arrangement direction. In addition, the flow control member is screw-connected to the screw rotation shaft, to be linearly moved in the tank member by a rotation of the screw rotation shaft while the fitted state is maintained. Preferably, the tank member has a non-round sectional shape, and the flow control member has a shape corresponding to the non-round sectional shape of the tank member. More preferably, the flow control member includes a valve member made of an elastic material, and a valve seat made of a rigidity material for fixing the valve member. In this case, the valve member is disposed to press-contact the inner surface of the tank member, and the valve seat is screw-connected with the screw rotation shaft to be separated from the inner surface of the tank member by a predetermined clearance.
Alternatively, the flow control member is disposed in the tank member to be rotatable around a rotation axis that is parallel to the tube arrangement direction where the tubes are arranged, and the flow control member is rotated in the tank member to change the ratio between the first number of the tubes in which the fluid flows, and the second number of the tubes in which the fluid does not flow. Even in this case, the air mixing function can be obtained by the flow control member disposed in the tank member of the heating heat exchanger. Specifically, in this case, the flow control member has a hollow-shaped portion opened at one end in the axial direction, and the hollow-shaped portion is provided with an outer periphery facing to one-side top ends of the tubes. Further, the outer periphery of the hollow-shaped portion has a seal surface for closing the one-side top ends of the tubes, and a recess portion for opening the one-side top ends of the tubes. In addition, the recess portion is provided in the hollow-shaped portion to have a spiral shape from one end toward the other end in the axial direction. Preferably, the heating heat exchanger further includes a seal member disposed between the seal surface of the hollow-shaped portion and the one-side top ends of the tubes, and the seal member is disposed to press-contact the seal surface.
Further, a drive shaft is disposed at the other end of the flow control member in the axial direction to protrude to an outside of the tank member, and an operation member is connected to the drive shaft at the outside of the tank member, for driving the drive shaft.
Preferably, the tank member includes an inlet tank for distributing the fluid into the tubes and an outlet tank for collecting the fluid from the tubes, and the flow control member is disposed in at least one of the inlet tank and the outlet tank. More preferably, the heating heat exchanger is one-way flow type in which the fluid flows through the tubes in one way from the inlet tank to the outlet tank. Alternatively, the inlet tank and the outlet tank are disposed at one end side of the core portion to be arranged adjacently in an air flowing direction, and the heating heat exchanger has a connection tank at the other end side of the core portion, opposite to arrangement positions of the inlet tank and the outlet tank. In addition, the inlet tank and the outlet tank are disposed to communicate with the connection tank through the tubes, such that the fluid from the inlet tank flows into the connection tank through the tubes, and flows from the connection tank into the outlet tank through the tubes after being U-turned in the connection tank. Further, the connection tank has therein a plurality of spaces partitioned from each other for each of the tubes arranged in the tube arrangement direction. Even in this case, the temperature of air blown into the passenger compartment can be suitably controlled using the flow control member disposed in at least one of the inlet tank and the outlet tank.
Preferably, a pressure-loss increasing portion is provided in the air conditioning case to increase an air pressure loss around a one tube among all the tubes, in which the fluid firstly flows. Therefore, it can prevent the temperature of air blown into the passenger compartment from being rapidly increased when an opening degree of the flow control member, for opening the tubes, is set at a very small degree from zero. Accordingly, temperature control performance of the vehicle air conditioner can be effectively improved. Alternatively, among all the tubes, one tube into which the fluid firstly flows is disposed at an outermost side in the core portion. Even in this case, the same advantages can be obtained.
Preferably, the heating heat exchanger is disposed in the air conditioning case to form a bypass passage in the air conditioning case at least at one side of the heating heat exchanger such that air flows through the bypass passage while bypassing the heating heat exchanger, and a bypass door is disposed in the air conditioning case for opening and closing the bypass passage.
Preferably, a partition member is disposed in the air conditioning case to partition the air passage at a downstream air side of the heating heat exchanger into a front passage and a rear passage. Further, the flow control member includes a front control part disposed to independently control the temperature of air flowing into the front passage, and a second control part disposed to independently control the temperature of air flowing into the rear passage. Therefore, the air temperature to be blown into a front seat area in the passenger compartment and the air temperature to be blown into a rear seat area in the passenger compartment can be independently controlled.
Preferably, a plurality of ribs are disposed at a downstream air side of the heating heat exchanger in the air conditioning case, for disturbing an air flow from the heating heat exchanger. Therefore, air mixing performance can be improved, and a temperature difference in air blown into the passenger compartment can be reduced. Alternatively, a guide member is disposed at a downstream air side of the heating heat exchanger in the air conditioning case, for guiding one of air from the first area and air from the second area to a side of the other one. Even in this case, the air mixing performance can be improved.